In a commercial lithium secondary battery used in this type of system, an organic electrolyte solution using a combustible organic solvent as a solvent is used. Thus, it is necessary to improve a structure and a material for the installation of a safety device for suppressing an increase in temperature upon short-circuiting and for the prevention of short circuit. Therefore, there has been suggested an all-solid-state lithium secondary battery in which a liquid electrolyte is changed to a solid electrolyte to solidify the entire battery (refer to a patent document 1). In this case, since the combustible organic solvent is not used in the battery, it is considered that the safety device can be simplified and that it is excellent in manufacturing cost and productivity.
However, in the case of the battery using the solid electrolyte material (sulfide-based solid electrolyte material) which is mainly composed of sulfide, there is such a problem that the sulfide-based solid electrolyte material reacts with moisture contained in the air or the like, thereby easily producing hydrogen sulfide. Therefore, the inhibition of the reaction is an essential issue in practical use. Regarding this, the patent document 1 discloses such a technology that the periphery of a battery cell is covered with an alkaline compound for detoxifying or neutralizing a hydrogen sulfide gas and that even if hydrogen sulfide is produced, it is detoxified by the alkaline compound trapping the hydrogen sulfide gas.